ATN on SPI L_Q for commands

Sriram Srinivasan srirams at
Tue Apr 3 06:27:14 PDT 2001

* From the T10 Reflector (t10 at, posted by:
* Sriram Srinivasan <srirams at>
  Can someone tell me what is the expected target behavior when the 
initiator asserts ATN on a SPI L_Q with a "Multiple Command" or a "Last 
Command" type?  Figure 74 (section 14.2) shows an arrow named "Attention 
Condition" from the SPI L_Q out to MESSAGE OUT ... and section 12.2 
  "g) .... the target shall enter the MESSAGE OUT phase at the 
completion of the current SPI information unit"
  So is this a way for an initiator to "change his mind" after sending 
an L_Q to assert ATN and make the target get out of the command flow?  
The SPI L_Q is being sent from the initiator, so HE is not the one 
detecting iuCRC errors, then why assert ATN on this SPI L_Q?  Other than 
section 12.2 and figure 74, there is no other place where SPI mentions 
what the target is expected to do after it receives the message.  Go BUS 
FREE, because all he got was a SPI L_Q and did not have any Command IU 
to go with the nexus?!?
  Please clarify,


 Sriram Srinivasan                       Sriram.Srinivasan at
 ASIC Design Engineer, LSI Logic,
 2001 Danfield Ct., 				Phone: 970-206-5847
 Fort Collins, CO 80525				FAX  : 970-206-5244

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